The invention relates to an electrically heatable primary catalytic converter having a metal housing, a catalyst provided in the housing and exposed to an exhaust gas stream, an electrical resistive heater and a connecting lead fed to the heater from the outside through an opening.
Primary catalytic converters of this type are known in a plurality of embodiments and have proved their value. However, it is disadvantageous that the electrical connecting lead is a problem. Thus, plastic-coated connecting leads are unsuited for a moisture- and gas-type connection at high temperatures and in corrosive media, as for example in the exhaust from internal combustion engines. In addition, clamp or screw connections made of conventional conducting materials, such as copper, nickel, or other alloys, cannot be used since they cannot ensure permanently reliable electrical connections because of the oxidation and/or corrosion of the interfaces. In particular, high contact resistances develop. On the one hand, if precious metals or precious metal coatings are used on the conducting materials, high costs result. On the other hand, the temperature in the connecting area of the primary catalytic converter can only be reduced by costly design measures. In view of the limited space for accommodation of such primary catalytic converters, functional disadvantages must be taken into account as a result of such measures, for example limitation of the exhaust gas stream to areas remote from the contacts.